FOODS AND FOOD HABITS 



43 



4% milk sugar, is the only important animal source. All 

 foods of vegetable origin, especially the cereals, wheat, corn, 

 oats, etc., furnish some starch. Peas, beans, and potatoes 

 all yield moderate amounts of starch only (Fig. 20.) This is 

 because potatoes contain much water, while peas, beans, etc., 

 are composed one third to one fourth of proteid. Leafy vege- 

 tables, e.g., cabbage, and lettuce, yield almost no food proper. 



Vegetable foods also contain sugars, though they are 

 not so common as starches and hence not so cheap. Sugar 

 cane and sugar beet provide us with the greatest quantity, 

 this sort of sugar being called saccharose. Fruits contain 

 considerable sugar of a type called fruit sugar, glucose or 

 dextrose. It is not so sweet as cane sugar, but its food value 

 is just as great. Chemists can easily make this form of sugar 

 from starch, and can produce it in this way quite cheaply. 

 i This fact has caused it to be used frequently in the adultera- 

 tion of cane sugar and very clear, colorless syrups. The 

 fact that it has very little sweetening power makes it necessary 

 to use more of it to produce the desired sweet taste; it 

 is, therefore, an undesirable adulterant for cane or for beet 

 sugar. 



PERCENTAGE OF CARBOHYDRATES IN COMMON FOODS 



